A Democratic super PAC is suing to accept and spend unlimited amounts of money to determine which party controls the Pennsylvania state Capitol in Harrisburg. / Matt Rourke, AP

by Fredreka Schouten, USA TODAY

by Fredreka Schouten, USA TODAY

WASHINGTON - A federal super PAC aligned with Democrats is suing to overturn Pennsylvania's law banning corporate and union contributions to political action committees - the latest sign that deep-pocketed super PACs are gearing up to shape state contests.

In its lawsuit, the General Majority PAC said it plans to get involved in legislative contests in the Keystone State this year and said the state's law is inconsistent with the Supreme Court's 2010 Citizens United decision allowing corporate and union spending in elections. That decision helped pave the way for super PACs to raise and spend unlimited amounts to help elect or defeat politicians as long as they operate independently of the candidates they support.

General Majority, previously known as the Fund for Jobs, Growth and Security, last year pumped more than $8 million into New Jersey contests to help Democrats retain control of the state legislature - even as Republican Gov. Chris Christie cruised to re-election.

In Pennsylvania, Republicans control both chambers of the state Legislature, with just a four-seat majority in the Senate. Half of the state Senate's 50 seats are up in November and all 203 seats in the General Assembly.

Organized labor has made Pennsylvania a key target after lawmakers began pushing a measure to end automatic payroll deductions of union dues from public employees' checks.

In all, more than 6,000 legislative seats in 46 states are in play this year, according to the tally by the National Conference of State Legislatures.

Jonathan Levy, super PAC's executive director, said the lawsuit's goal is to clarify how independent expenditures will work in Pennsylvania in the post-Citizens United era. (Many legal experts say states will be forced to allow some form of super PACs as a result of the high court's ruling, and lawsuits such as these are viewed as a step to nudge states to comply with Citizens United.)

In an e-mail, Levy said the group still is looking at states around the country to determine where it will play a role in elections.

General Majority is working "to counteract the bottomless pockets of people like the Koch brothers," Levy said, referring to the billionaire brothers Charles and David Koch, who have helped finance Republican groups. "Led by our partners from labor, we beat them in New Jersey, and we expect to keep taking the fight to them wherever it's needed."

Republicans also are working to dismantle remaining obstacles to super PACs at the state level.

Last month, a super PAC aligned with Republican Sen. David Vitter, filed a lawsuit challenging Louisiana's cap on contributions to PACs. The super PAC has been established by Vitter's allies to spend unlimited amounts on his 2015 bid for governor.